A conventional electric power steering system, which includes a motor and an electronic control unit (ECU) is disclosed in JP 2003-204654 A (JP 3593102, US 2003/0127921 A1). According to this electric power steering system disclosed, an ECU and a motor are integrated into one unit and a connector is used as for electrically connecting signal wires of a rotation angle sensor and the ECU.
The connector hinders size reduction of the system. Since parts cost of the connector is high, cost of the electric power steering system is necessarily high.